Composite building panels of the type that typically have a sheet metal outer shell that is then infilled with a concrete material are well known. Typically, these panels are rectangular in side profile and include alongside edges corresponding tongue and grove features to allow for interlocking of like panels to form a wall.
Such panels are very effective at resisting fire and have a very long time to complete failure once compromised as they maintain their structural integrity. Even if significant cracks occur in a wall made of such panels (which typically occur at the join) and flames can pass through, the remainder of the wall will remain in place so that only a small amount of flames are able to pass through, thereby restricting the spread of fire. Accordingly, a fire can burn within the building without catastrophic failure and even during a large scale fire, the wall contributes to the structural integrity of the building even when damaged. This is in contrast to plaster panels having a fire resistant coating, which tend to reach catastrophic failure very quickly once the coating has been damaged and the core of the material is exposed to the fire and heat.
It has been observed that in most building fires there is a limited availability of fuel so that if the walls can remain in place without failure, the fire will eventually burn out without catastrophic building failure. This is particularly true in apartment complexes where previous fires have led to wall failure and then spread quickly through the building, leading to large human and financial cost.
Furthermore, due to their strength composite panels having a sheet metal outer shell and concrete infill are better able to resist seismic loading without catastrophic failure compared to other commonly used internal wall systems. Even if a small amount of damage occurs during the seismic event the fire rating of the wall remains high, which is important as fires often follow seismic events.
Previous composite panels, such as those described in Australian patent no. 707873 for example, have a tongue having a square or generally rectangular profile, which provides some resistance to buckling, though due to the shallow tongue creates gaps in the wall that can reduce fire ratings. In panels having a square tongue, the stress of the wall is carried at the base of the tongue, thereby limiting its strength. Also, other previous panels have had a tongue with a general wedge shape that, when engaged with a corresponding groove under force, acts to open up the groove under buckling loads or when a force is applied to one side, thereby limiting the strength of the wall. The result is that the weakest point of a wall made with such panels is the interface or join between two adjacent panels.
It is also known to add grooves or ridges within the structure of the panel for decorative purposes and to improve the visual appearance by preventing bubbling and/or oil canning. It has been discovered that composite building panels of this kind can suffer from a failure problem when subjected to a sudden and sever vibratory load. This type of load can occur when a building that has been constructed from these types of composite building panels is subjected to an earth tremor or earthquake.
While subjected to a severe vibratory load, the interface between the inner wall of the outer shell and the concrete infill material may slip, relative to one another. This can impose excessive compressive and/or strain load on the concrete material, causing the concrete material to lose its structural integrity and for the entire panel to fail, sometimes catastrophically.
In another mode of failure, as the composite building panel is subjected to the tensile and compressive loads imposed upon it by a geological event, the outer shell may buckle and/or rupture, and this may also cause the concrete infill material to catastrophically fail. Other typical modes of failure attributed to geological events are caused by the likely aftershocks that occur.
There is a need to address the above, and/or at least provide a useful alternative.